Digital video cameras capture frames at a frame rate and with a frame resolution by help of an image capturing device being for instance a complementary metal-oxide semiconductor (CMOS) or a charge coupled device (CCD). The frame rate and the frame resolution result in a capture data rate.
For professional applications, frame rate and resolution need to be high. So, the capture data rate of professional video equipment is high as well.
Captured frames need to be stored. For storage in real-time, the storage data rate has to meet the capture data rate. But, commonly used slow memorizing devices like flash memories do have storage data rates which are significantly lower than said high capture data rate resulting in professional applications.
Therefore, a memory array comprising several flash memories is used. The flash memories in the memory array are provided with data in parallel. So, the storage data rate of the memory array equals the cumulated storage data rates of the flash memories comprised in said memory array. The ratio of the video camera's capture data rate to a single flash memory's storage rate gives the minimal number of flash memories which need to be comprised in the memory array for ensuring that the memory array's storage data rate meets the video camera's capture data rate.
For synchronizing purposes the flash memory array is connected to the video camera's image capturing device via a buffer, for instance a dynamic random access memory (DRAM).
A frame or part of a frame captured is transferred from the image capturing device to the buffer. Simultaneously to transferring a next captured part or frame, each flash memory in the flash memory array is provided with a portion of the buffered data. The size of said portion corresponds to the storage data rate of the flash memories.
Flash memories are organized in memory blocks. If some data in a given memory block shall be changed, even data remaining unchanged but being comprised in said given memory block needs to be re-written.
The fractions provided to a flash memory are much smaller than said memory blocks which results in storage of fractions of several frames in the same memory block.
So editing a frame after capturing requires erasing and rewriting all memory blocks comprising a fraction of said frame.
Disadvantageously, memory blocks allow only for a limited number of erasing/writing cycles which limits the life span of flash memories.
There is a need to elongate the life span of said flash memories arrays used in video sequence recording applications while maintaining a constant editing rate.